The present invention claims the benefit of Korean Patent Application No. P2000-42849 filed in Korea on Jul. 25, 2000, which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to displays, and more particularly, to a display with micro light modulators in which light is modulated for displaying a picture.
2. Background of the Related Art
For the next generation of display, there has been active research on different types of Flat Panel Displays (FPDs). The most popular displays of this research have been the Liquid Crystal Display (LCD) that employs the electro-optical properties of liquid crystal and the Plasma Display Panel (PDP) that employs plasma induced by electron discharge.
The LCD not only has the drawbacks of a narrow viewing angle and a slow response to video signals, but also has a complicated fabrication process since the Thin Film Transistors (TFTs) and electrodes used in a LCD are formed using semiconductor fabrication processes. Although the PDP has an advantage of a simple fabrication process that is desirable for manufacturing large sized displays, the PDP has the drawbacks of a high power consumption, low luminance due to poor discharge efficiency and relatively high cost.
There has been a development of a new display that solves the foregoing problems in flat panel displays. The new display uses a micro light modulator having Micro Electromechanical Systems (MEMS), an extra hyperfine machining technology, in every pixel for displaying a picture.
A related art display with a micro light modulator will be explained with reference to the attached drawings. FIG. 1 illustrates a plan view of a representative related art display with micro light modulator.
Referring to FIG. 1, the related art display with micro light modulator is provided with a plurality of fixed electrodes 13 formed in parallel at fixed intervals on a substrate 11, a plurality of movable electrodes 15 formed in parallel at fixed intervals over, between and in the same direction as the fixed electrodes 13. The ends of the movable electrodes 15 extend outward more than the ends of the fixed electrodes 13, and the sides of the movable electrodes 15 respectively overlap adjacent fixed electrodes 13 of the display.
When no voltage is applied between the fixed electrode 13 and the movable electrode 15, the movable electrode 15 is separated by a distance from the fixed electrode, and thus light from back light (not shown) under a substrate 11 is transmitted through to a display surface above the movable electrode. When a voltage is applied between the fixed electrode 13 and the movable electrode 15, the movable electrode 15 is brought into contact with the fixed electrode 13, and thus no light is transmitted through.
FIGS. 2A and 2B illustrate cross sections along line A-Axe2x80x2 in FIG. 1, wherein it can be seen that the fixed electrodes 13 are formed in parallel at fixed intervals on the substrate 11, and the movable electrodes 15 are formed so as to be overlapped with the fixed electrodes 13 on both sides thereof. The fixed electrodes 13 are formed as stripes on the substrate 11. Both ends of the movable electrodes 15 are affixed (not shown) to the substrate 11 and the central portion of the movable electrodes 15 is separated by a distance from the fixed electrodes 13. The central portion of the movable electrodes 15 is movable in up and down direction in response to an electrical signal applied between the movable electrodes 15 and the fixed electrodes 13.
FIG. 2A illustrates a cross section showing the electrodes of a representative portion of the display, e.g. a pixel in an off state. Initially, incident light from a back light 19 on a back side of the substrate 11 emanates through a space between the fixed electrodes 13 and the movable electrodes 15. A preset level of voltage applied between the fixed electrodes 13 and the movable electrodes 15 induces an attraction between the fixed electrode 13 and the movable electrode 15 through an electrostatic force. As result of the application of a preset voltage, the movable electrodes 15 come into contact with adjacent fixed electrodes 13 and thus, turns the pixel off by cutting off the incident light from a back light 19 on a back side of the substrate 11.
As shown in FIG. 2B, when no voltage is applied between the fixed electrodes 13 and the movable electrodes 15, the movable electrodes 15 are maintained at or restored to an original state by elastic force to being separated by a distance from the fixed electrodes 13. The distance between the fixed electrodes 13 and the movable electrode 15 enable incident light from the back light 19 to transmit so as to turn on the pixel. For reference, the elastic material layer 17 positioned under the movable electrodes 15 is used for the elastic force.
FIG. 2C illustrates a section along line B-Bxe2x80x2 in FIG. 1, wherein it can be seen that the ends of the movable electrodes 15 are formed on the substrate 11 at fixed intervals. Since the related art display with a micro light modulator has movable electrodes 15 that all have the same width and length, all of the movable electrodes 15 will move simultaneously at the same driving voltage level. The relationship of transmissivity through the related art micro light modulator and driving voltage V between the fixed electrodes 13 and the movable electrodes 15 is illustrated in FIG. 3. The driving voltage at which there is no transmissivity through a micro light modulator is known as the threshold voltage.
Referring to FIG. 3, since the related art micro light modulator has essentially only two levels of transmissivity, it is required that the related art display be driven by a time-division driving circuit for implementing gray levels, in which timing for applying a voltage to a given pixel is constantly changed. Therefore, the related art requires additional driving circuitry, which makes the overall circuitry for the display complicated.
Accordingly, the present invention is directed to a display with micro light modulators that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a display with micro light modulators, in which a micro light modulators is used for implementing a gray level without a separate driving circuit.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the display with micro light modulators includes a transparent substrate, a plurality of fixed electrodes on the substrate, a plurality of movable electrodes over and between the fixed electrodes, each movable electrode having a size different from one another and overlapping portions of adjacent fixed electrodes, and a back light on a back surface of the substrate.
In another aspect of the present invention, there is provided a display with a micro light modulator including a substrate, a plurality of fixed electrodes on the substrate, a plurality of movable electrodes each having first micro supports at both lengthwise ends and a second micro support at a location between the first micro supports, wherein each of the movable electrodes has a second micro support at a location different location from the other movable electrodes, and wherein each of the movable electrodes are formed over and between the fixed electrodes, and overlaps portions of adjacent fixed electrodes, and a back light on a back surface of the substrate.
In another aspect of the present invention, there is provided a display with a micro light modulator including a substrate, a plurality of fixed electrodes on the substrate, a plurality of movable electrodes each having at least one micro support, wherein each of the movable electrodes overlap with portions of adjacent ones of the fixed electrodes, an insulating material layer positioned under each of the movable electrodes; and a back light on a back surface of the substrate.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.